Indwelling ureteral catheter stents or drainage tubes have been used to maintain urinary drainage. In the past, stents made of straight lengths of open end tubing have been used for this purpose and have provided good drainage for sustained periods of time. However, the use of such open end tubing has not been completely satisfactory. For example, in some instance, the tubing has migrated and in others it has been expelled.
Various attempts have been made to produce stents which do not have the problems which accompany the use of such tubing. For example, stents have been designed which are closed at one end (hereinafter referred to as the "proximal end") to facilitate passage into a body passage and which have at the other end (hereinafter referred to as the "distal end") a flange to make upward migration of the stent less likely. Another approach has been to provide the body of the stent with sharply pointed barbs which are designed to prevent downward migration and expulsion. However, such barbs increase the diameter of the stent making it more difficult to insert and in some instances can cause the stent to migrate outside the bladder.
In U.S. Pat. No. 4,212,304 issued July 15, 1979 and U.S. Pat. No. 4,307,723 issued Dec. 29, 1981, ureteral stents are disclosed which have a hook at the proximal end and distal end. The gently curved hooks which can be straightened with a guide wire to facilitate insertion and removal of the stent are surprisingly effective in preventing migration and expulsion. The patented stents are widely accepted because they can be easily introduced both endoscopically and during open surgery.
All the commercially available stents have one disadvantage in common; the length of the available stents cannot be readily reduced to a shorter length desired by a surgeon without removing the means which reduce the tendency of the stent to migrate or to be expelled. As a result, the available stents have to be provided in a variety of predetermined lengths.